Crankcase pressure control



Dec. 5, 1950 R. E. BROWN CRANKCASE PRESSURE CONTROL Filed Dec. 9, 1948 INVENTOR RICHARD E. finawzv y w ATTORNEYS moves a piston toward the crankcase causes a slight pressure therein which tends to escape out of the openings 28 causing the valve 29 to assume the dot-dash position indicated in Fig. 2. This air passes outwardly through the openings 26 and on out through the annular filter I9 and through the annular opening 36 at the lower portion of cap 16. This outward flow is generally at a very low velocity and usually will not carry oil out but any oil or oil mist will strike the screens in the filter element [9 so that the same is not carried outside. Upon the next stroke of the engine or compressor which causes a piston to move away from the crankcase space, the crankcase volume will be increased but the valve 29 will have c.0sed over the openings 28 and therefore no air can enter the crankcase and a slight vacuum will be produced. Thus, my invention creates a slight vacuum almost immediately after the engine or compressor starts. After this, there is very little flow inward or outward through my device but the pressure in the crankcase will fluctuate very slightly due to the strokes of the engine or compressor while maintaining a slight vacuum within the crankcase.

If there were no fiow inwardly through my relief valve and breather cap, no filter element l9 would be needed. As a matter of fact, this is only desirable in order to take care of the blow-by volume in the crankcase.

It is often desirable to provide a very small bleed hole such as that indicated at 37 through the valve 29 opposite one of the openings 28. Another suitable location for such a bleed hole is shown by the arrow 38. In other words, the bleed hole could be a very small opening through the wall of the member 18. The provision of such a bleed hole is desirable especially in one-cylinder engines or in engines or compressors of the twocylinder opposed type which, upon the suction stroke, causes a high displacement in the crankcase. If the high vacuum is not relieved in such a case the bearings may be sucked dry.

I have thus provided very simple but novel means wherein the flexible rubberlike valve 29 opens very easily upon the creation of a slight pressure in the crankcase and closes quickly thereafter so as to maintain a slight vacuum in the crankcase.

While I have shown my device as communicating with atmosphere at the zone 36, it should be understood that it is equally applicable in those instances where crankcase gases are drawn away through positive suction applied to the pipe I I. This is particularly true where the posi tive suction device operates in such a way as to exert alternate suction and pressure. In such a case the device shown in Fig. 2 is placed in the line leading to the source of alternate suction and pressure. When suction is exerted, the valve 29 opens to allow a small amount of the crankcase gases to be sucked out. When the pressure portion of the cycle occurs on the downstream side of the valve 29, obviously the valve 29 will be pushed to its closed position so as to maintain the slight vacuum in the crankcase.

What I claim is:

1. In combination with a crankcase having a breather pipe, a cap of downwardly opening cup shape adapted to fit over the upper end of said breather pipe, an annular series of openings through said cap, a flexible valve overlying said openings on the upper face of said cap, and means securing the center of said valve to said cap.

2. In combination with a crankcase having a breather pipe, a cap of downwardly opening cup shape adapted to fit over the upper end of said breather pipe, an annular series of openings through said cap, a flexible valve overlying said openings on the upper face of said cap, means securing the center of said valve to said cap, a flange extending radially outwardly from the lower edge of said cap, an annular filter element resting on said flange, and a second cap of cup shape opening downwardly, said second cap secured to said first named cap and engaging the top of said filter element.

3. In combination with a crankcase having an upstanding breather pipe, a cap of downwardly opening cup shape adapted to fit over the upper end of said pipe, a partition extending diametrically across said cap and spaced from the upper end thereof, an annular series of openings through said partition, a flexible valve overlying said openings and having its center only secured to said partition, a flange extending radially outwardly from the lower edge of said cap, an annular filter element resting on said flange, a second cap of downwardly opening cup shape having its central top portion removably secured to said partition wall, and there being openings for air flow between said second cap and said filter element and between said filter element and the interior of said first named cap above said partition.

4. The combination of claim 3 including a passageway for restricted air flow from the interior of said first named cap below said partition outwardly to atmosphere.

RICHARD E. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,432,187 J erkins et a1 Oct. 17, 1922 1,943,765 Jones Jan. 16, 1934 2,375,718 Winkels et al May 8, 1945 FOREIGN PATENTS Number Country Date 347,770 Germany Jan. 24, 1922 

